Preparation for cleaning metal preparatory to painting



Patented Apr. 10, 1928.

' UNITED STATES 1,665,465 PATENT OFFICE.

JAMES D. KLINGER AND GLETE L. BOYLE, DETROIT, MICHIGAN.

PREPARATION FOR CLEANING METAL PREPAR A'IORY TO PAINTING.

No Drawing.

Our invention relates to an improved preparation for cleaning metal, particularly sheet steel, preparatory to painting the metal.

The invention concerns itself particularly in the provision of a suitable solvent to be used in conjunction with a rust attacking and removing acid for the removal of rust, oxides, dirt, oils and greases from the surlo face of sheet steel or metal parts and also from the pores of the metal, in order to satisfactorily clean the same preparatory to painting.

A solvent which we have discovered to be unusually valuable in a solution of this character is known to the chemical art as ethyl methyl ketone or it may be written as methyl ethyl ketone having the formula CH COC H or C,H,,O.

Man different solvents and combinations thereo have been used in conjunction with various rust removing acids for cleaning metal for painting. Solvents such as butyl alcohol, fusel oil, ethyl acetate, mesityl oxide as and others have been employed in the art 'with varying degrees of success. One of the most pronounced objectionable features of these several solvents has been that they must first be blended with ethyl alcohol or acetone to make them miscible with the particular rust removing acid in connection with which they are used, which usually contains a certain percentage of water. Consequently when the cleaning solution is applied to the metal the acetone or ethyl alcohol evaporates, thus throwing the principal solvents out of solution, thereby creating a condition which makes it difiicult to satisfactorily rinse all the resultant products of 40. cleaning which contain the solvents that are normal y insoluble in water from the surface of the metal. There are, however, cer-. tain solvents such as diaceton'e alcohol and phorone, which when blended with ethyl alcohol seem to prevent the lower boiling point solvents from evaporating, but afterlending they lose a certain amount of their solvent properties which lowers their value as cleaning agents.

Ethyl methyl ketone possesses the very desirable property of being an excellent sol vent for oils and greases, and furthermore,

it is miscible alone in .an acid solution.

Therefore, it can be used in any desired percentage in an acid cleaning solution, the

amount used depending upon the prevailing J is as follows:

Application filed December 26, 1925. Serial No. 77,879.

conditions for cleaning. If evaporation occurs it will only lower the percentage of the ethyl methyl ketone present, and it will not disturb the stability of the solution, with the result that after the cleaning operation is completed the remaining products of cleaning can be readily rinsed from the metal with hot or cold water.

Free or undisturbed rinsing on account of the resultant products of cleaning being rinsed from the pores of the metal as well as from the surface, insures a much cleaner surface over which to paint. Free rinsing, however, is onl feasible when all the ingredients used 1n the cleaning solution are miscible in varying proportions in the metal etching acid used and in water. It is highly important that the resultant products of cleaning be very thoroughl rinsed from the surface ofthe metal especially if the metal is to be painted with a pyroxylin primer or coated with any p roxylin material.

In order to pro uce a satisfactory cleaning solution the ethyl methyl ketone may be blended with a rust removing acid such as phosphoric acid or with a sulphuric acid. A suita le rust inhibiting agent such as a reduced chromium compound may with advantage be added to the admixture.

When phosphoric acid is used the solution should be rinsed from the metal with hot water. Phosphoric acid is a syrupy or a sticky acid and eat care should'be exercised in rinsing in or er to remove all of the phosphoric acid from the surface of the metal and also the ores of the metal. By using sulphuric acid and a reduced chromium compound the difliculty of rinsing can be minimized because sulphuric acid has a decided aflinity for water and is consequently a free rinsing acid and is readily removable from the pores of the metal as well as from its surface. 1

When phosphoric acid is employed a satisfactory formula is as follows:

2d5% by volume ortho phosphoric acr 85% by volume water,

40% by volume ethyl meth lketone.

When the sulfuric acid re uce chromium solution is employed a satisfactory formula Dissolve one fourth of a ound of normal sodium chromate in one an one-half quarts of water and add one-half quart of concen trated sulfuric acid. The solution is allowed to cool. It is then reduced with any suitable reducing agent such as a satisfactory carbohydrate until the characteristic bluish green color of reduced chromium compounds predominates. Two quarts of the ethyl methyl ketone are then added to complete the admixture.

This solution may be applied with a brush, sponge or spray to the surface of the metal to be cleaned and after the metal has been cleaned the resultant products of clean ingnlay be removed therefrom with hot or cold water. When small parts are cleaned they may be dipped or immersed in a tank containing cleaning solution and subsequently dipped in a tank containing the rinse Water. After rinsing the metal is dried and is then ready for the priming coat of paint.

In the cases Where rapid cleaning of the metal is desired or to lessen the cost of the material used, denatured alcohol may be substituted for a part of the methyl ethyl ketone in varying amounts. An amount equal to twenty-five per cent by volume of the solution is satisfactory. Denatured alcohol might be employed in a proportion varying from fifteen to thirty-five er cent by volume with fifteen per cent and upwards of the ethyl methyl ketone.

\Vhat we claim is:

1. A preparation for cleaning metal for painting, comprising an admixture of phosphoric acid and ethyl methyl ketone in substantially the proportions herein set forth.

2. A preparation for cleaning metal for painting, comprising an admixture of a dilute rust attacking and removing acid, and ethyl methyl ketone in substantially the proportions herein set forth.

In testimony whereof, we sign this specification.

JAMESD, KLINGER. CLETE L. BOYLE. 

